With the development of wireless multimedia service, the demands of people for high data rate and good user experience are gradually increasing, and thus higher requirements are made on system capacity and coverage of the traditional cellular network. In the traditional Long Term Evolution (LTE) cellular network, a macro base station is used as a unique access side network element to provide an access service for User Equipment (UE). In order to satisfy the demands of users for higher data rate and improve the spectral efficiency of the cellular network, 3rd Generation Partnership Project (3GPP) introduces a Low Power Node (LPN) as a supplement to the macro base station to provide the access service for the UE. LPN has the features of low cost, low power consumption, easy deployment and the like. Usually, there are two deployment scenarios, i.e., hot-spot deployment and enhanced coverage, the data rate of high-rate data services in indoor and outdoor hot-spot areas can be effectively improved, and the coverage of the remote area or cell edge is improved. Usually, LPN may also be called a small base station, such as a Home eNB (HeNB), a picocell (pico), a Remote Radio Unit/Remote Radio Head (RRU/RRH), a Relay Node (RN) or the like. Under the hot-spot deployment scenario, in order to get higher data rate and spectral efficiency, a great number of small base stations need to be densely deployed in an area. However, since the coverage range of small cells under the small base stations is relatively small, the probability of handover failure increases when a UE moving at medium and high speed passes through the small base stations, and consequently the UE service continuity is influenced. In order to improve the UE mobility performance after the small cells are introduced, the industry puts forward a method for providing higher data rate and satisfying user electricity saving demands by the way that a certain base station (such as a macro base station) guarantees the fundamental coverage, the UE always keeps a Radio Resource Control (RRC) connection with the certain base station and the small cell is only used as a Transmission Point (TP). In this system architecture, the UE keeps the connections with at least two base stations and uses the radio resources under the two base stations, such that cross-node radio resource aggregation can be realized. This architecture is usually called a dual-connection architecture, as illustrated in FIG. 1. In the two base stations connected with the UE, one base station which has a certain management and control capability is usually called a Master eNB (MeNB) and the other base station is called a Secondary eNB (SeNB). After the UE accesses the MeNB, the dual connection may be realized through an SeNB adding process. After the SeNB is successfully added, a series of management such as SeNB modification, SeNB deletion and SeNB change and the like may be performed on the SeNB, herein SeNB modification refers to modifying parameters when the UE accesses the SeNB, and SeNB change refers to deleting the SeNB and adding a new SeNB.
In the dual-connection architecture, a user plane has three possible architectures. As illustrated in FIG. 2, in architecture option 1, an S1-U interface between a base station and a Serving Gateway (SGW) is terminated at an MeNB and an SeNB; in architecture option 2, the S1-U interface is terminated at the MeNB, and at a Radio Access Network (RAN) side there is no bearer separation; and in architecture option 3, the S1-U interface is terminated at the MeNB, and at the RAN side there is bearer separation, e.g., after downlink data in Evolved Packet System (EPS) bearers arrive at the MeNB, a part of data in one bearer may be separated to the SeNB and then are transmitted to the UE by the SeNB. According to the user plane protocol stack architecture of the SeNB, the above-mentioned three architectures may be further divided. At present, the dual connection may adopt architecture 1A in architecture option 1 or architecture 3C in architecture option 3. Architecture 1A as illustrated in FIG. 3 adopts architecture option 1, and the user plane protocol stack on the SeNB has an independent Packet Data Convergence Protocol (PDCP) layer and protocol layers below, and there is no bearer separation. Architecture 3C as illustrated in FIG. 4 adopts architecture option 3, and the user plane protocol stack on the SeNB has an independent Radio Link Control (RLC) protocol layer and protocol layers below.
In another aspect, in the dual-connection architecture, an HeNB is possibly used as an MeNB or SeNB. Due to the requirement that the HeNB only provides services for specific users, a concept of Closed Subscriber Group (CSG) is introduced, and each CSG has a unique identifier, i.e., CSG ID. In LTE, cells of three different access modes are defined for the HeNB, i.e., CSG cell (which corresponds to a closed mode HeNB and can be accessed by a UE which is registered as a member of the CSG), hybrid cell (which corresponds to a hybrid mode HeNB and can be accessed by any terminal, but the UE which is registered as the member of the CSG can access with an identity of higher-priority member), open cell (which corresponds to an open mode HeNB and can be accessed by any UE). The access mode and the CSG ID of the HeNB can be known through air interface broadcasting. If the HeNB does not broadcast the CSG ID and the CSG indication, the cell is an open cell; if the HeNB broadcasts the CSG ID and the CSG indication with a value of “true”, the cell is a CSG cell; and if the HeNB broadcasts the CSG ID and the CSG indication with a value of “false”, the cell is a hybrid cell. A core network element and a UE respectively store CSG subscription information, including a CSG ID list that the users can access with identities of members. Under the scenario of HeNB existing in the dual-connection architecture, CSG related functions need to be supported, for example, access control based on CSG member identities. For a closed cell, a UE with member identity can only be allowed to access, and for a hybrid cell, whether the UE is a member or a non-member needs to be determined and the base station needs to perform corresponding admission control or rate control aiming at different member identities. However, there is no CSG access control method aiming at the scenario of HeNB existing in the dual-connection architecture in the existing art.